title: Towards a new classification of the Arthoniales (Ascomycota) based on a three-gene phylogeny focussing on the genus Opegrapha.
abstract: A multi-locus phylogenetic study of the order Arthoniales is presented here using the nuclear ribosomal large subunit (nuLSU), the second largest subunit of RNA polymerase II (RPB2) and the mitochondrial ribosomal small subunit (mtSSU). These genes were sequenced from 43 specimens or culture isolates representing 33 species from this order, 16 of which were from the second largest genus, Opegrapha. With the inclusion of sequences from GenBank, ten genera and 35 species are included in this study, representing about 18% of the genera and ca 3% of the species of this order. Our study revealed the homoplastic nature of morphological characters traditionally used to circumscribe genera within the Arthoniales, such as exciple carbonization and ascomatal structure. The genus Opegrapha appears polyphyletic, species of that genus being nested in all the major clades identified within Arthoniales. The transfer of O. atra and O. calcarea to the genus Arthonia will allow this genus and family Arthoniaceae to be recognized as monophyletic. The genus Enterographa was also found to be polyphyletic. Therefore, the following new combinations are needed: Arthonia calcarea (basionym: O. calcarea), and O. anguinella (basionym: Stigmatidium anguinellum); and the use of the names A. atra and Enterographa zonata are proposed here. The simultaneous use of a mitochondrial gene and two nuclear genes led to the detection of what seems to be a case of introgression of a mitochondrion from one species to another (mitochondrion capture; cytoplasmic gene flow) resulting from hybridization.
authors.affiliation: National Botanical Garden of Belgium, Department of Cryptogamy, Domaine de Bouchout, B-1860 Meise, Belgium. damien.ertz@br.fgov.be
authors.forename: Damien
authors.initials: D
authors.lastname: Ertz
authors.forename: Jolanta
authors.initials: J
authors.lastname: Miadlikowska
authors.forename: François
authors.initials: F
authors.lastname: Lutzoni
authors.forename: Steven
authors.initials: S
authors.lastname: Dessein
authors.forename: Olivier
authors.initials: O
authors.lastname: Raspé
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vigneron
authors.forename: Valérie
authors.initials: V
authors.lastname: Hofstetter
authors.forename: Paul
authors.initials: P
authors.lastname: Diederich
mesh_terms: D001203:Ascomycota / Q000145:classification* / Q000235:genetics / Q000648:ultrastructure; D001499:Bayes Theorem; D003470:Culture Media; D005656:Fungal Proteins / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000235:genetics; D016533:Mycological Typing Techniques; D009687:Nuclear Proteins / Q000235:genetics; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins